The Ohio Department of Agriculture confirmed cases of Eastern Equine Encephalitis (EEE) in two horses that died on a farm in Mercer County. This is the first incident of EEE in Ohio since an outbreak in 1991 in Wayne and Holmes counties. At this time, there are no known human illnesses associated with this confirmation. Eastern Equine Encephalitis is caused by a virus that can infect birds, horses and humans. It is transmitted by mosquitoes, and outbreaks typically occur in late summer and early fall when mosquitoes are most abundant. Infected horses could experience symptoms including paralysis, impaired vision, difficulty swallowing, hanging their heads and grinding their teeth. An effective equine vaccine exists for EEE. Typically, infected horses with clinical symptoms die within three to five days after onset of clinical signs. There is no treatment for EEE aside from supportive care. Veterinarians who suspect EEE in an animal they have treated should contact the Ohio Department of Agriculture Animal Disease Diagnostic Laboratory.